Investigation of the limits of unconventional ammonia synthesis
Chemical Engineering and Processing - Process Intensification, cilt.216, 2025 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 216
- Basım Tarihi: 2025
- Doi Numarası: 10.1016/j.cep.2025.110429
- Dergi Adı: Chemical Engineering and Processing - Process Intensification
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC
- Anahtar Kelimeler: Ammonia, Membrane, Microchannel reactor, Modeling, Process intensification
- Boğaziçi Üniversitesi Adresli: Evet
Özet
Intensified NH3 synthesis is modeled in a Fe-based catalyst-coated, in-situ cooled microchannel reactor (MR) comprising a ZnCl2-IMS (Immobilized Molten Salt) membrane. NH3 produced in the reaction (R) channel is separated to the neighboring permeate (P) channel hosting sweep N2 flow that regulates temperature to <623 K. A low-cost model is formulated and successfully benchmarked with the comprehensive counterpart and experimental data. MR configurations are modeled to elucidate the effects of catalytic activity, NH3 permeance, sweep gas-to-reactive stream ratio (SR), and flow partitioning on the interplay between NH3 production, separation, and heat transfer. At 613 K, 50 bar, H2/N2 = 3 and 1.5 × 10–3 m3 kgcat-1 s-1, the 47.4 % N2 conversion exceeds the equilibrium limit (42 %) and the membraneless counterpart (14 %). Under identical conditions, a two-fold increase in the reaction rate and NH3 permeance gives 91 % N2 conversion. Increasing SR promotes N2 conversion and NH3 recovery, but decreases NH3 fraction in the P channel, a metric for the post-NH3 separation by a secondary membrane separator. While co-current dosing to the R and P channels offers slightly higher N2 conversions, the identically operated counter-current mode gives higher NH3 recovery. The findings provide guidelines for the opportunities and limitations of the membrane-separation driven NH3 synthesis.